Paragia cf. decipiens Shuckard, 1837 (Ogloblin 1923); Paragia decipiens Shuckard, 1837; Paragia tricolor Smith, 1850 (Hofeneder 1928).

South Australia: Gawler (Ogloblin 1923; Hofeneder 1928).

Differing from most genera in following combination of characters. Mandibles protruding distinctly from mandibular capsule, reaching or slightly projecting beyond cephalic edge (Fig. 10A). Maxilla anteriorly directed, strongly sclerotized. Maxillary bases conspicuously wide, connected in midline along birth opening. Anterior part of maxilla pointed (Fig. 10A). In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally. Cephalothorax mostly pale.

Shape and coloration. Cephalothorax distinctly longer than wide, length 2.0 mm, maximum width 1.76 mm. Anterior head margin not protruding. Thorax nearly straight. Meso-metathoracic border slightly constricted (Fig. 9C). Coloration with distinct pattern of different pale brown shades; usually medially pale and slighter darker laterally in ventral and dorsal view.

Figure 9. 

Nipponoxenos vespularum Kifune & Maeta, host, male, female, cephalothorax, photomicrographs A Vespula shidai Ishikawa, Sk. Yamanne & Wagner stylopized by male of N. vespularum, lateral view B detail of host abdomen with male puparium inside C ventral side of female cephalothorax D dorsal side of female cephalothorax. Abbreviation: sbmm – segmental border between mesothorax and metathorax.

Head capsule. Almost ⅓ as long as entire cephalothorax including lateral cephalic extensions. Coloration mostly pale brown, but darker on lateral extensions and on distinctly sclerotized maxillae (Fig. 10A). Clypeal area delimited from labral area, slightly protruding anteriorly, forming inconspicuous, slightly pigmented clypeal lobe (Fig. 10A); clypeal sensilla present. Border between clypeal and frontal region distinct. Cuticle of frontal region slightly wrinkled. Segmental border between head and prothorax indistinct dorsally but indicated by coloration; on ventral side separated by birth opening medially and by suture laterally.

Figure 10. 

Nipponoxenos vespularum Kifune & Maeta, anterior part of female cephalothorax, photomicrographs A anterior part of cephalothorax, ventral side B Anterior part of cephalothorax, dorsal side. Abbreviations: cll – clypeal lobe, md – mandible, mx – vestige of maxilla (maxilla), pp – pigmented papillae.

Supra-antennal sensillary field. Not delimited by furrow mesally.

Antenna. Presence or absence of antennal vestige not verified.

Labrum. Ventral labral field elliptic, not protruding but slightly convex. Dorsal labral field elliptic, ~ 5× wider than long, slightly arcuate. Presence or absence of labral sensilla not verified.

Mandible. Anteromedially directed at angle of 60°, distinctly protruding from mandibular capsule, reaching or slightly projecting beyond anterior edge of head (Fig. 10A). Bulge not distinctly raised. Sensilla not examined. Mandibular tooth narrow or moderately widened, pointed apically.

Maxilla. Anteriorly directed, pointed, strongly sclerotized. Bases wide, connected medially. Apical region not projecting beyond mandible anteriorly. Presence of palp vestige not verified. Submaxillary groove slightly produced.

Labium. Labial area inserted between maxillae, slightly pigmented medially; anteriorly delimited by mouth opening and posteriorly by connected maxillary bases.

Mouth opening. Mouth opening slightly curved, sclerotized along margin.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders vaguely indicated ventrally by pigmented stripes with specific cuticular surface, but nor recognizable on dorsal side (Fig. 9C, D). Border between metathorax and abdomen marked by ridge and change of cuticular sculpture and pigmentation. Entire abdominal segment I darker than thorax. Cuticle of thoracic segments on ventral side wrinkled or reticulate, with several small, pigmented papillae on prothorax. Prosternal extension undifferentiated, evenly arched. Dorsal side of thorax mostly smooth. Meso- and metathorax unmodified in shape, transverse. Setae and cuticular spines on lateral region of abdominal segment I not examined.

Spiracles. Situated on posterior ⅓ of cephalothorax, slightly elevated, with anterolateral orientation.

Less pigmented than in other genera of Xenidae. With conspicuous, nearly black clypeus and very short and black genae, very distinct on lightly colored surrounding areas of cephalotheca (Fig. 11). Antennal vestige very large (Fig. 11A).

Figure 11. 

Nipponoxenos vespularum Kifune & Maeta, male, cephalotheca, photomicrographs A frontal view B lateral view. Abbreviations: a – vestigial antenna, cl – clypeus, coe – compound eye, gn – gena, mxb – maxillary base.

Shape and coloration. Rounded laterally in frontal view, widely elliptic (Fig. 11A); rounded in lateral view (Fig. 11B). Coloration pale except for clypeus and genae (Fig. 11).

Cephalothecal capsule. Compound eyes with individual ommatidia well visible. Clypeus black colored; inconspicuous clypeal lobe straight in frontal view; sensilla mainly concentrated on clypeal lobe and on lateral parts of clypeus. Frontal region not deformed, lacking frontal impression. Occipital bulge rather indistinct. Diameter of genae (black) between maxillary base and compound eye very small, subequal to antennal diameter (Fig. 11A). Occipital bulge absent.

Supra-antennal sensillary field. Kidney-shaped and bulging, delimited medially by quite indistinct furrow.

Antenna. Antennal vestige very large, with complete torulus. Periantennal area distinctly delimited.

Labrum. Labral area distinct. Setae of dorsal field present.

Mandible. Anteromedially directed. Coloration darker anteriorly and less pigmented posteriorly. Bulge pointed.

Maxilla. Distinct, prominent. Coloration darker anteriorly, posterior part around vestige of palp less pigmented.

Labium and hypopharynx. Located between and below maxillae. Praementum and postmentum distinct, separated by slightly paler coloration of postmentum. Hypopharyngeal protuberance inconspicuous.

Mouth opening. Mouth opening distinctly arcuate, nearly U-shaped.

One of the earliest diverging lineages of Xenidae with a Palearctic origin (Benda et al. 2019). Placed either as sister to Tachytixenos Pierce + Paraxenos Saunders or as the earliest diverging group, sister to all other Xenidae (Benda et al. 2021).

Monotypic, restricted to East Asia.

Vespula spp. (Vespidae: Vespinae).

The monotypic Nipponoxenos was originally described as a subgenus of Xenos by Kifune and Maeta (1975). We classify it as a valid genus, based on a molecular phylogeny (Benda et al. 2019) and morphological characters newly reported here.

Vespula flaviceps (Smith, 1870) (as Vespula lewisi Cameron, 1903) (Kifune and Maeta 1975); Vespula flaviceps flaviceps (Smith, 1870) (Kifune and Yamane 1991), Vespula shidai Ishikawa, Sk. Yamanne & Wagner, 1980 (Nakase and Kato 2013).

Japan: Honshu; Russia: Primorskij Kraj, Ussurijsk (Kifune and Yamane 1991).

This species was described under the monotypic subgenus Nipponoxenos Kifune and Maeta 1975.

Differing from the other genera by a specific shape of the mandibular tooth, which is very wide basally and reaches the area of mandibular bulge. Tooth with pointed, ventrally directed apex. Base of tooth ventrally covered with small depressions continuous with several rows of spines (Fig. 14E). Prosternal extension undifferentiated (compared to similar genus Paraxenos), evenly arched, without any swelling or color differentiation. Maxillae distinctly prominent as in Pseudoxenos, Tuberoxenos, and some Paraxenos species. Mandible not protruding from capsule. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Shape and coloration. Cephalothorax compact, ca. as long as wide, or slightly wider than long, or vice versa. Size varying strongly within genus, length 0.94–1.82 mm, width 0.88–1.88 mm. Anterior head margin evenly rounded or projecting. Thorax slightly widening posteriorly. Coloration comprising multiple brown shades and distinct patterns (Fig. 12C, D).

Figure 12. 

Tachytixenos cf. indicus Pierce, host, female, cephalothorax, photomicrographs A Tachytes sp. stylopized by female of T. cf. indicus, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax.

Head capsule. Approximately ¼ ~ ½ as long as entire cephalothorax including lateral extensions. Coloration variable, pale, completely dark brown, or forming specific color pattern. Clypeal area well delimited from labral area, arcuate, or slightly protruding anteriorly forming clypeal lobe. Surface of clypeal area smooth or slightly wrinkled. Sensilla (~ 40–55) regularly dispersed over clypeal surface or mainly concentrated on clypeal lobe. Border between clypeal and frontal region present but indistinct. Frontal region smooth or slightly wrinkled. Dorsal segmental border between head and prothorax distinct or only recognizable.

Supra-antennal sensillary field. Smooth with dispersed sensilla, delimited by distinct furrow on medial side (Fig. 13B).

Figure 13. 

Tachytixenos cf. indicus Pierce, female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviations: fssf – furrow of supra-antennal sensillary field, paa – periantennal area.

Antenna. Preserved as poorly defined area with several minute rounded plates, antennal sensilla, or cavity, in some cases all three combined. Periantennal area smooth, flat, or forming incomplete elliptic wall between antenna and supra-antennal sensillary field (Fig. 13C, D).

Labrum. Ventral field wider than long, elliptic. Dorsal field slightly arcuate, at least 3× wider than long in midline. Dorsal field bearing ~ 15–30 setae inserted in cavities.

Mandible. Anteromedially directed at angle of 40–65°, enclosed in mandibular capsule. Mandibular bulge not distinctly raised, with several sensilla. Cuticle completely smooth to slightly sculptured. Mandibular tooth very wide on its base, reaching area of mandibular bulge. Tooth ventrally directed and pointed apically. Base with small depressions continuous with several rows of spines (Fig. 14E).

Figure 14. 

Tachytixenos cf. indicus Pierce, female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: bcm – brood canal membrane, md – mandible, mdt – mandibular tooth, mdts – spine of mandibular tooth.

Maxilla. Well-developed, prominent, and clearly separated from labial area, strongly sclerotized, directed anteriorly or anteromedially. Not or very slightly overlapping with mandible proximally, not projecting beyond mandibular apex anteriorly. Cuticle usually smooth, rarely wrinkled. Vestige of palp distinct, forming small bulge with more or less distinct plates, situated medially on ventral side of maxilla. Submaxillary groove slightly produced posterolaterally.

Labium. Labial area between maxillae distinct, delimited anteriorly by mouth opening and posteriorly by birth opening. Wider than long in midline and flat or convex. Cuticular surface smooth or slightly reticulated.

Mouth opening. Mouth opening arcuate, sclerotized along margin.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders more or less distinct, usually separated by mesal furrows, often combined with pigmented stripes or spots on dorsal side. Border between metathorax and abdomen usually formed by ridge. Cuticle of thoracic segments on ventral side reticulate, with small scattered pigmented papillae. Dorsal side of thorax smooth or slightly reticulated. Prosternal extension undifferentiated, evenly arched. Shape of meso- and metathorax unmodified, transverse. Setae present on lateral region of abdominal segment I. Cuticular surface distinctly sculptured in cases with sparse setation (Fig. 13E).

Spiracles. Located on posterior ~ ⅓ of cephalothorax, slightly elevated, with lateral, anterolateral, or dorsal orientation.

Genus characterized by combination of distinct paired furrow of supra-antennal sensillary field (Fig. 15A, D) and shape of mandibular tooth. Mandibular tooth very wide on its base and reaching area of mandibular bulge. Tooth base with small depressions continuous with several rows of spines (Fig. 15E, see also 14E). Diameter of genae between maxillary base and compound eye at least 2× as large as diameter of vestigial antenna.

Figure 15. 

Tachytixenos cf. indicus Pierce, male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: fssf – furrow of supra-antennal sensillary field, gn – gena, mdt – mandibular tooth.

Shape and coloration. Shape of cephalotheca rounded laterally in frontal view, widely elliptic. Anteriorly pointed in lateral view. Coloration forming pattern of pale and dark shades.

Cephalothecal capsule. Compound eyes with darker individual ommatidia well visible on pale background. Clypeal lobe straight in frontal view, distinctly prominent in lateral view. Sensilla mainly concentrated on clypeal lobe. Frontal region with paired furrow of supra-antennal sensillary field, lacking frontal impression. Diameter of genae between maxillary base and compound eye large, ~ 3× as large as diameter of vestigial antenna. Occipital bulge absent.

Supra-antennal sensillary field. Kidney-shaped and bulging, delimited medially by distinct furrow. Furrows relatively wide and not interconnected anteriorly (Fig. 15A, D).

Antenna. Of standard shape, small, with complete torulus. Periantennal area not distinctly delimited. Sensilla present (Fig. 15C).

Labrum. Labral area distinct. Setae on dorsal field present.

Mandible. Mandible anteromedially directed. Mandibular tooth very wide on its base and reaches area of mandibular bulge. Tooth base with small depressions continuing in several rows of spines (Fig. 15E). Mandibular bulge bears several sensilla.

Maxilla. Maxilla distinct, prominent, completely dark. Vestige of maxillary palp distinct.

Labium and hypopharynx. Well-developed between and below maxillae, completely dark. Praementum and postmentum slightly separated by furrow. Hypopharyngeal protuberance absent.

Mouth opening. Mouth opening well visible, not covered by ventral labral field, slightly arcuate.

One of the earliest diverging lineages of Xenidae. Forming a clade of Palearctic origin with its sister genus Paraxenos (Benda et al. 2019).

Monotypic, restricted to the Old World.

Tachytes spp. (Crabronidae: Crabroninae).

The monotypic genus Tachytixenos was described by Pierce (1911) but only superficial descriptions of the female and male without illustrations were provided. Hofeneder (1949) synonymized it with Pseudoxenos, but it was later classified as Paraxenos by Kinzelbach (1971b). We restored Tachytixenos from synonymy and classify it as a valid genus based on monophyly revealed by the molecular phylogeny (Benda et al. 2019, 2021) and based on morphological characters newly reported here

Cook (1919) noted that Bohart synonymized Tachytixenos with Pseudoxenos but it was done laterally by Hofeneder (1949).

Tachytes xenoferus Rohwer, 1911; T. maculicornis Saunders, 1910; T. modestus Smith, 1856 (Pierce 1911; Kinzelbach 1978; Kifune and Hirashima 1980); T. vischnu Cameron (Cook 2019).

Algeria; India: Deesa; Thailand: Peninsular Siam; China; Sri Lanka (Pierce 1911; Kinzelbach 1978; Kifune and Hirashima 1980); Denmark? (Cook 2019).

Benda et al. (2021) reported two lineages possibly representing separate species. A more comprehensive sampling and a detailed study are necessary for a taxonomic revision of this genus.

Differing from Tachytixenos by a narrower mandibular tooth and a differentiated prosternal extension. Prosternum with anterior swelling (Fig. 18A) similar to Paragioxenos, or with distinct color pattern. Clypeal sensilla well visible, extending to ventral side of clypeal area. Vestige of antenna preserved as cavity (Fig. 17D), additional rounded plates rarely present. Maxillae of two types, fused with labial area or distinctly separated and prominent as in Tachytixenos, Pseudoxenos, and Tuberoxenos. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Shape and coloration. Compact, very variable in shape, distinctly longer than wide, or wider than long. Size very variable, length 0.94–1.9 mm, maximum width 0.8–2.57 mm. Anterior head margin distinctly protruding. Thorax slightly widening posteriorly, sometimes subparallel. Coloration varying from light to dark brown. Cephalothorax displaying multiple brown shades forming distinct patterns (Fig. 16C, D).

Figure 16. 

Paraxenos erberi Saunders, host, male, female, cephalothorax, photomicrographs A Bembecinus peregrinus (Smith) stylopized by P. erberi, lateral view B detail of host abdomen with female under third tergite and male puparium under fourth tergite C ventral side of female cephalothorax D dorsal side of female cephalothorax.

Head capsule. Ca. ⅓–½ as long as entire cephalothorax including lateral extensions. Coloration pale to dark, always with species specific patterns. Clypeal area not delimited or well separated from labral area, protruding anteriorly, always forming clypeal lobe. Surface smooth or very slightly wrinkled. Very distinct sensilla mainly concentrated on clypeal lobe and extending to ventral side of clypeal area. Border between clypeal and frontal region usually not clearly recognizable but present, rarely more distinct. Frontal region distinctly wrinkled or covered by papillae. Segmental border between head and prothorax very indistinct on dorsal side, in most specimens virtually unrecognizable.

Figure 17. 

Paraxenos sp., female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviation: a – vestigial antenna.

Supra-antennal sensillary field. Smooth or slightly wrinkled, with dispersed sensilla, delimited by distinct furrow on medial side (Fig. 18B).

Figure 18. 

Paraxenos sp., female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: fssf – furrow of supra-antennal sensillary field, ps – prosternal swelling, sbhp – segmental border between head and prothorax, smxg – submaxillary groove.

Antenna. Preserved as cavity (Fig. 17D), rarely combined with rounded plates. Antennal sensilla or vestigial setae missing. Periantennal area smooth, sometimes reduced when supra-antennal sensillary field almost reaches vestige of antennae.

Labrum. Ventral field distinctly wider than long, elliptical or semicircular. Dorsal field arcuate to nearly straight, > 3× wider than long in midline. Dorsal field with ~ 20–25 setae inserted in cavities.

Mandible. Anteromedially directed at an angle of 30–65°, enclosed in mandibular capsule or rarely protruding from it. Mandibular bulge not distinctly raised, with ~ 5–18 sensilla. Cuticle completely smooth, or partially sculptured on articulatory area. Mandibular tooth narrow or slightly widened, pointed or blunt, armed with distinct spines.

Maxilla. Very variable, well-developed and separated from labial area, or fused with it and strongly reduced. Cuticle always smooth. Prominent, anteriorly or anteromedially directed, in some cases partially overlapping with mandible proximally. Distal maxillary region not projecting beyond mandible anteriorly. Vestige of palp distinct, forming cavity or small bulge with more or less distinct plate. Located anteriorly or medially on ventral side of maxilla. Submaxillary groove distinctly produced posterolaterally (Fig. 18A).

Labium. Labial area between maxillae distinct, delimited anteriorly by mouth opening and posteriorly by birth opening. Wider than long in midline and flat. Cuticular surface smooth or slightly reticulated.

Mouth opening. Distinctly arcuate to straight, sclerotized around margin.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders more or less distinct, usually separated by mesal furrows on ventral side, rarely combined with pigmented stripes or spots on dorsal side, but not recognizable dorsally in most specimens. Border between metathorax and abdomen usually formed by ridge. Cuticle of thoracic segments reticulate on ventral side, often with small, scattered pigmented papillae. Dorsal side of thorax smooth or slightly reticulated. Prosternal extension anteriorly with arcuate to semicircular swelling in most species, or lacking swelling but with distinct color pattern. Meso- and metathorax unmodified in shape, transverse. Setae and cuticular spines present on lateral region of abdominal segment I (Fig. 17E).

Spiracles. On posterior third of cephalothorax, slightly elevated, with anterolateral or anterodorsal orientation.

Characterized by distinct and relatively wide furrow of supra-antennal sensillary field (Fig. 19A, D). Differing from sister genus Tachytixenos in shape of the mandibular tooth, which is conspicuously pointed and not in contact with mandibular bulge. Diameter of genae between maxillary base and compound eye 2× or several times larger than diameter of vestigial antenna. Cephalotheca of elliptic shape in frontal view.

Figure 19. 

Paraxenos erberi Saunders, male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: fssf – furrow of supra-antennal sensillary field, mdt – mandibular tooth.

Shape and coloration. Elliptic and rounded laterally in frontal view, also almost rounded in lateral view. Coloration forming pattern of pale and dark shades.

Cephalothecal capsule. Compound eyes with darker individual ommatidia well visible on pale background. Clypeal lobe straight in frontal view, not prominent in lateral view. Sensilla dispersed on clypeal surface. Frontal region with paired furrow of supra-antennal sensillary field, lacking impression or occipital bulge. Diameter of genae between maxillary base and compound eye very large, > 3× as large as diameter of vestigial antenna.

Supra-antennal sensillary field. Kidney-shaped and bulging, delimited medially by distinct furrow. Furrows relatively wide, not connected anteriorly (Fig. 19A, D).

Antenna. Of standard shape, small, with small plates and cavity (Fig. 19C), torulus interrupted. Periantennal area not clearly delimited from supra-antennal sensillary field.

Labrum. Labral area distinct. Setae present on dorsal field.

Mandible. Anteromedially directed. Tooth apically pointed, not very wide basally, not reaching area of mandibular bulge (Fig. 19E), which bears sensilla.

Maxilla. Distinct, prominent. Coloration pale centrally and dark laterally. Vestige of palp distinct, dark.

Labium and hypopharynx. Labium distinct between and below maxillae, dark. Praementum and postmentum indistinctly separated by furrow. Hypopharyngeal protuberance present or not.

Mouth opening. Well visible, not covered by ventral labral field, slightly arcuate.

Forming a clade of Palearctic origin with Tachytixenos (Benda et al. 2019).

Thirteen described species, distributed in the Old World and Australia.

Bembecinus, Bembix and Stizus spp. (Bembicidae: Bembicinae).

Paraxenos was described by Saunders (1872) but only a superficial description of the male was provided. Kinzelbach (1971b) synonymized several additional genera with Paraxenos, all of them described by Pierce (1908, 1909, 1911, 1919) from the New World (Eupathocera, Opthalmochlus, Homilops, Sceliphronechthrus) and Old World (Tachytixenos). He also classified Bembicixenos described by Székessy (1955) as subgenus of Paraxenos, but later considered it a synonym of Paraxenos (Kinzelbach 1978). We classify Paraxenos as a valid genus based on monophyly revealed by a molecular phylogeny (Benda et al. 2019, 2021) and based on morphological characters newly reported here.

Bembix musca (Handlirsch, 1893) (Kifune and Hirashima 1987).

Australia: Queensland (Kifune and Hirashima 1987).

Stizus marthae Handlirsch, 1892 (Pasteels 1951).

Algeria (Pasteels 1951).

Bembecinus antipodum (Handlirsch, 1892) (Székessy 1956).

New Guinea (Székessy 1956).

Bembecinus hungaricus (Frivaldsky, 1876); Bembecinus peregrinus (Smith, 1856); Bembecinus tridens (Fabricius, 1781) (Saunders 1872; Kinzelbach 1978).

Algeria; Europe (Kinzelbach 1978).

Sphecius nigricornis (Dufour, 1838), Stizus biclypeatus (Christ, 1791), Stizus bizonatus Spinola, 1839, Stizus pubescens (Klug, 1835), Stizus ruficornis (Fabricius, 1787) (Pasteels 1956; Kinzelbach 1978).

Algeria; Cyprus; Egypt; Greece; India; Jordan; Tajikistan (Kinzelbach 1978; Batelka and Straka 2005); Senegal? (Kinzelbach 1978).

Stizus ruficornis (J. Förster, 1771) (as Stizus distinguendus Handlirsch, 1901) (Luna de Carvalho 1978a).

Senegal (Luna de Carvalho 1978a).

Bembix oculata Panzer, 1801, Bembix rostrata (Linnaeus, 1758), Bembix sp. (Kinzelbach 1978).

Czech Republic; Germany; Hungary; Italy; Mongolia; Spain (Székessy 1955; Kinzelbach 1978; Benda et al. 2021); Turkey (this study).

Bembix orientalis (Handlirsch, 1893) (Kifune and Hirashima 1987).

Sri Lanka (Kifune and Hirashima 1987).

Bembecinus bimaculatus (Matsumura & Uchida, 1926) (Kifune and Yamane 1985).

Japan (Kifune and Yamane 1985).

Bembecinus gazagnairei (Handlirsch, 1892) (Székessy 1956).

New Guinea (Székessy 1956).

Bembix atrifrons (F. Smith, 1956) (Kifune and Hirashima 1987).

Australia: Western Australia (Kifune and Hirashima 1987).

Bembecinus braunsii (Handlirsch, 1894) (as Sphecius fraunsi Handlirsch, 1894) (Pasteels 1956).

Democratic Republic of Congo (Pasteels 1956).

Stizus basalis Guérin-Méneville, 1844 (Pasteels 1956).

Mali: Djenné (Pasteels 1956).

Maxilla distinctly reduced, flattened, anteriorly rounded, not distinctly prominent; fused to labial area but well defined by its strong sclerotization, conspicuous compared to usually pale cephalothorax as in Nipponoxenos and some species of Xenos. Maxillary bases appear connected and fused to each other. Vestigial palps differ from those of all other genera, preserved only as inconspicuous concavity on wrinkled maxillary surface, without any vestigial plate. Located anteriorly on ventral side of maxilla, at level of mandibles (Fig. 22E). Clypeal area not delimited from labral area, apparently more or less fused (Fig. 22D). Mandible nested in capsule. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Shape and coloration. Compact and usually ovoid, ca. as long as wide, or slightly wider, rarely longer than wide. Abdominal segment I of some species extruded laterally, forming corner below abdominal spiracles. Species relatively variable in size, length 0.76–1.62 mm, maximum width 0.72–1.74 mm. Anterior head margin evenly rounded or protruding. Thorax slightly to strongly widening posteriorly, sometimes subparallel. Coloration mostly pale, with light shadows of brown dominating. Some parts of cephalothorax, especially maxillae, dark and sclerotized.

Head capsule. Including lateral extensions ~ ⅓–½ as long as entire cephalothorax. Color pattern formed by shades of pale and dark brown, with maxillae always dark. Clypeal area not delimited from labral area, apparently more or less fused, slightly or distinctly protruding anteriorly, always forming clypeal lobe (Fig. 22D). Surface wrinkled apically on clypeal lobe (sometimes with lamellar structures), smooth ventrolaterally and dorsally. Clypeal surface with ~ 50–70 sensilla or more. Border between clypeal and frontal region indistinguishable. Frontal area smooth. Segmental border between head and prothorax difficult to recognize on dorsal side in some specimens.

Supra-antennal sensillary field. Smooth or slightly wrinkled, with dispersed sensilla. Not delimited or indistinctly by furrow on medial side.

Antenna. Preserved only as elongated depression or inconspicuous furrow (Fig. 21C). Rounded plate, small cavity or sensilla missing. Periantennal area slightly wrinkled or smooth.

Labrum. Ventral field slightly wider than long, nearly circular. Dorsal field anterior to mouth opening slightly arcuate, at least 4× wider than long at midline, with setae inserted in cavities on surface.

Mandible. Anteriorly to anteromedially directed at angle of 40–70°, enclosed in capsule. Mandibular bulge sometimes indistinct, with up to ten spine-shaped or blunt sensilla, or lacking these structures. Cuticle completely sculptured or partially smooth. Tooth narrow, armed with several rows of spines.

Maxilla. Reduced and not protruding, fused to labium but clearly indentifiable by distinct sclerotization; appearing connected and fused medially, with sclerotization continuous along birth opening. Cuticle distinctly wrinkled. Apical maxillary region almost reaching upper edge of mandible in some species. Vestige of palp present as inconspicuous cavity on wrinkled maxillary surface, lacking vestigial plate. Located anteriorly on ventral side, at level of mandibles. Maxillary base slightly raised and less sclerotized than anterior region (Fig. 20C). Submaxillary groove slightly produced posterolaterally.

Figure 20. 

Brasixenos araujoi (Oliveira & Kogan), host, female, cephalothorax, photomicrographs A Apoica pallens (Fabricius) stylopized by female of B. araujoi, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax. Abbreviations: mx – vestige of maxilla, mxb – maxillary base.

Labium. Labial area recognizable between maxillae but fused with them, anteriorly delimited by mouth opening; convex, wider than long in midline, pale laterally, strongly sclerotized medially and around mouth opening. Cuticular surface smooth or wrinkled, with wrinkles indistinct on well sclerotized areas.

Mouth opening. Arcuate to distinctly U-shaped, sclerotized around margin.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders more or less distinct, usually indicated by pigmented stripes or changed coloration on dorsal side. Mesal furrows absent. Border between metathorax and abdomen usually indicated by change in coloration or cuticular sculpture, separating ridge indistinct. Cuticle of thoracic segments with smooth surface on the ventral side, in some cases with small scattered pigmented papillae. Dorsal side of thorax usually completely smooth. Prosternal extension not very distinctly prolonged, usually evenly arched. Thoracic segments constricted laterally, distance between lateral extensions of head and spiracles thus reduced (Fig. 20D). Setae and cuticular spines present on lateral region of abdominal segment I (Fig. 21E).

Figure 21. 

Brasixenos araujoi (Oliveira & Kogan), female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviation: a – vestigial antenna.

Figure 22. 

Brasixenos araujoi (Oliveira & Kogan), female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviation: mxp – vestige of maxillary palp.

Spiracles. Spiracles situated on posterior half or posterior third of cephalothorax, slightly elevated, with anterolateral orientation.

Differing from other genera by fusion of maxilla with cephalotheca. Maxillary cuticular surface with longitudinal grooves (Fig. 23E). Vestige of maxillary palp visible (distinct in optical microscope, very inconspicuous on SEM micrographs) (Fig. 23A, D).

Figure 23. 

Brasixenos sp., male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: cl – clypeus, fi – frontal impression, mx – vestige of maxilla, mxp – vestige of maxillary palp.

Shape and coloration. Laterally rounded in frontal view, elliptic, in lateral view pointed anteriorly. Coloration mostly dark, but with some lighter areas such as ocular region or surroundings of maxillary palps (Fig. 23A).

Cephalothecal capsule. Compound eyes with darker individual ommatidia well visible on pale ocular background. Clypeus with longitudinal pale line (Fig. 23A). Clypeal lobe arcuate or straight in frontal view, prominent in lateral view; with sensilla evenly dispersed. Frontal region with conspicuous impression (Fig. 23D). Diameter of genae between maxillary base and compound eye large, > 2× as large as diameter of vestigial antenna. Occipital bulge absent.

Supra-antennal sensillary field. Kidney-shaped and bulging, medially delimited by frontal impression, with visible but indistinct furrows.

Antenna. Of standard shape, small, with complete torulus. Periantennal area indistinct but present. Sensilla usually absent.

Labrum. Labral area well visible but dorsal field not clearly separated from clypeus. Setae on dorsal field present.

Mandible. Anteromedially directed, pale centrally and dark laterally. Mandibular bulge not conspicuous, with several sensilla.

Maxilla. Not recognizable as separate structure, fused with cephalotheca. Cuticular surface of maxillary area sculptured, with longitudinal grooves (Fig. 23E). Vestige of palp well visible (with light microscope, very indistinct on SEM micrographs) (Fig. 23A, D).

Labium and hypopharynx. Distinct, inserted between and below maxillae, completely dark. Praementum and postmentum very indistinctly separated. Hypopharyngeal protuberance recognizable, not well delimited.

Mouth opening. Well visible, U-shaped, partially covered by ventral labral field.

Sister to a large clade containing representatives of genera previously known as Pseudoxenos, Paraxenos, and Xenos (Benda et al. 2019).

Group of Xenidae with origin in the New World and restricted to this region. Comprising seven species, all of which are known from Brazil.

Various genera of Epiponini (Vespidae: Polistinae).

The genus Brasixenos was described and differentiated from Xenos by Kogan and Oliveira (1966), but the description of the female cephalothorax was superficial. Although Kinzelbach (1971b) treated Brasixenos as a junior synonym of Xenos, Trois (1988) attempted to reinstate Brasixenos as a valid genus. Nevertheless, no author has followed this opinion (Cook 2019). Although Kogan and Oliveira (1966) expected a close relationship of Xenos with Brasixenos in their description, Benda et al. (2019) revealed the group as a separate lineage unrelated to Xenos. We classify Brasixenos as a valid genus, based on a molecular phylogeny (Benda et al. 2019, 2021) and morphological characters newly reported here.

Polybia sp., close to Polybia sericea (Olivier, 1792).

Brazil: Rio de Janeiro (Kogan and Oliveira 1966).

Apoica pallens (Fabricius, 1804) (Oliveira and Kogan 1962); Apoica flavissima Vecht, 1973; Apoica thoracica Buysson, 1906 (this study).

Brazil: Amazonas (Oliveira and Kogan 1962).

Polybia ignobilis (Haliday, 1836).

Brazil: Bahia (Kogan and Oliveira 1966).

Polybia sericea (Olivier, 1792).

Brazil: Rio de Janeiro, Pará (Kogan and Oliveira 1966).

Polybia ignobilis (Haliday, 1836) (as Polybia atra Saussure, 1854).

Brazil: Rio de Janeiro (Kogan and Oliveira 1966).

Polybia (Myrapetra) paulista Ihering, 1896 (Trois 1988).

Brazil (Trois 1988).

Polybia tinctipennis Fox, 1898 (as Polybia ypiranguensis Ihering, 1904) (Kogan and Oliveira 1966).

Brazil: Rio de Janeiro (Kogan and Oliveira 1966).

Differing from its sister genus Eupathocera in the following characters. Frontal region with conspicuous coverage of papillae (Fig. 25F). Supra-antennal sensillary field with wrinkled surface, which almost reaches vestigial antenna. Periantennal area small and indistinct (Fig. 25C). Prothorax ventrally connected to head on same plane, versus usually elevated in Eupathocera (Fig. 25A). Position of sensilla on clypeal lobe not extended onto ventral side of clypeal area as in Xenos or Paraxenos. Rudiments of torulus usually preserved (Figs 25C, 29D). Mandible not protruding from mandibular capsule. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Shape and coloration. Cephalothorax compact and usually ovoid, varying distinctly in shape, longer than wide to distinctly wider than long. Species relatively variable in size, length 0.88–1.7 mm, maximum width 0.72–1.68. Anterior head margin evenly rounded or slightly protruding anteriorly. Thorax slightly to strongly widening posteriorly, sometimes subparallel. Coloration of cephalothorax with multiple dark and light brown shades forming distinct pattern (Fig. 24C, D).

Figure 24. 

Leionotoxenos bishoppi (Pierce), host, female, cephalothorax, photomicrographs A Monobia quadridens (Linnaeus) stylopized by female of L. bishoppi, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax.

Head capsule. Ca. ⅓ to nearly ½ as long as entire cephalothorax including lateral cephalic extensions. Coloration variable, pale to dark brown or forming specific patterns. Clypeal area well delimited from labral region, clypeal lobe indistinct or slightly protruding anteriorly. Surface more or less wrinkled, in some cases with reticulated pattern (Fig. 26D), with 12–26 (or more) sensilla distributed anteriorly. Border between clypeal and frontal region indistinct but still recognizable. Frontal region with conspicuous coverage of papillae (Fig. 25F). Dorsal border between head and prothorax indicated by interrupted suture, distinct coloration, or largely obliterated.

Figure 25. 

Leionotoxenos bishoppi (Pierce), female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviations: a – vestigial antenna, at – antennal torulus, frp – frontal papillae, lehc – lateral extension of head capsule, paa – periantennal area, pst – prosternum (prosternal extension), ssf – supra-antennal sensillary field.

Figure 26. 

Leionotoxenos bishoppi (Pierce), female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: cll – clypeal lobe, fr – frontal region, ssf – supra-antennal sensillary field.

Supra-antennal sensillary field. Conspicuously wrinkled or reticulated. Usually delimited by indistinct furrow on medial side, but otherwise by change in cuticular sculpture, with wrinkled surface of supra-antennal sensillary field versus papillae on frontal region (Fig. 26B).

Antenna. Preserved as more or less defined area, with several rounded plates and setae (Fig. 25C). Torulus largely reduced or absent, rudiment usually recognizable as interrupted furrow (Fig. 25C). Periantennal area small and indistinct, supra-antennal sensillary field with wrinkled surface almost reaching antennal vestige (Fig. 25C).

Labrum. Ventral field wider than long, elliptic. Dorsal field slightly arcuate, at least 3× to 4× wider than medially along midline. Dorsal field with several inconspicuous setae (10 to 20) inserted in cavities.

Mandible. Anteromedially directed at an angle of 40–55° and enclosed in capsule. Mandibular bulge more or less distinctly raised, with 5–7 sensilla. Cuticle smooth to slightly sculptured or with longitudinal grooves. Mandibular tooth narrow or slightly widened, with or without spines.

Maxilla. Reduced and not distinctly protruding, fused to labium, often not clearly separated from labial area. Cuticle smooth or slightly wrinkled. Maxillary apex not projecting beyond mandible anteriorly. Vestige of palp inconspicuous, forming small bulge, sometimes very indistinct, located medially on ventral side of maxilla. Submaxillary groove more or less distinctly produced posteriorly to maxillary base.

Labium. Labial area flat, wider than long in midline or as wide as long, usually recognizable between maxillae but sometimes fused with them. Anteriorly delimited by mouth opening and posteriorly by birth opening. Cuticular surface smooth or slightly reticulated.

Mouth opening. Distinctly arcuate to nearly straight, sclerotized marginally.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders distinct or indistinct, usually indicated by mesal furrows, often combined with pigmented stripes. Border between metathorax and abdomen usually formed by indistinct ridge or change in cuticular surface. Cuticle of thoracic segments on ventral side reticulate, often with scattered small and pigmented papillae. Dorsal side smooth or slightly wrinkled or reticulated. Prosternal extension either undifferentiated or indicated anteriorly by color pattern, in which case a swelling can be present or absent. Region of prosternal extension evenly connected to head on same plane (Fig. 25A). Meso- and metathorax unmodified in shape, transverse. Setae or cuticular spines present on lateral region of abdominal segment I (Fig. 25E).

Spiracles. Located on posterior ~ ⅓ of cephalothorax, slightly elevated, with anterolateral or anterodorsal orientation.

Differing from other genera in the following characters. Diameter of genae between maxillary base and compound eye at least 2× as large as diameter of vestigial antenna. Distinct paired furrow of supra-antennal sensillary field absent. Cephalotheca always of elliptic shape (Fig. 27A). Frontal fissure very distinct (Fig. 27D). Maxilla prominent, at least 1.5× longer than basally wide (Fig. 27E).

Figure 27. 

Leionotoxenos sp., male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: fi – frontal impression, mx – vestige of maxilla, ob – occipital bulge.

Shape and coloration. In frontal view rounded laterally, elliptic, in lateral view pointed anteriorly. Coloration with pattern of pale and dark shades.

Cephalothecal capsule. Compound eyes with darker individual ommatidia well visible on pale ocular background. Clypeal lobe arcuate in frontal view, prominent in lateral view. Clypeal sensilla mainly concentrated medially on clypeus. Frontal region slightly deformed by frontal impression (Fig. 27D). Occipital bulge present (Fig. 27D). Diameter of genae between maxillary base and compound eye very large, ~ > 3× as large as diameter of vestigial antenna.

Supra-antennal sensillary field. Kidney-shaped and bulging, medially delimited by frontal impression, lacking distinctly visible furrows.

Antenna. Of standard shape, small, with complete torulus and small plates (Fig. 27C). Periantennal area not clearly delimited from supra-antennal sensillary field.

Labrum. Labral area distinct. Setae on dorsal field present.

Mandible. Anteromedially directed. Tooth pointed apically, not reaching area of mandibular bulge basally. Bulge set with sensilla.

Maxilla. Distinct, prominent, entirely dark. Vestige of palp distinct.

Labium and hypopharynx. Distinct, dark, inserted between and below maxillae. Praementum and postmentum clearly separated by furrow. Hypopharyngeal protuberance not present.

Mouth opening. Distinctly arcuate but not well visible, covered by ventral labral field.

According to Benda et al. (2019) part of a clade of a New World origin, with Eupathocera Pierce as sister group.

Fourteen described species, restricted to the New World.

Various genera of Odynerini (Vespidae: Eumeninae).

The genus Leionotoxenos was described by Pierce (1909) based on his suggestion that a new genus of Strepsiptera should be established if it utilizes a different host genus. No diagnosis or description was presented. It was later synonymized with Pseudoxenos (Bohart 1937) and then with Paraxenos (Kinzelbach 1971b). We restore Leionotoxenos from synonymy and classify it as a valid genus, based on the molecular phylogeny (Benda et al. 2019, 2021) and morphological characters newly reported here. We classify the names Monobiaphila and Montezumiaphila as synonyms of Leionotoxenos.

Euodynerus annulatus arvensis (Saussure, 1869) (as Odynerus (Leionotus) arvensis Saussure, 1869) (Pierce 1911), Euodynerus annulatus sulphureus (Saussure, 1858) (Kinzelbach 1971b).

USA: Illinois (Pierce 1911).

Monobia quadridens (Linnaeus, 1763) (Pierce 1909).

USA: Texas (Pierce 1909), Kansas, Pennsylvania (this study).

Euodynerus foraminatus (Saussure, 1853) (as Odynerus foraminatus Saussure, 1853) (Pierce 1911).

USA: New Jersey (Pierce 1911).

Stenodynerus proquinquus (Saussure, 1870) (as Odynerus (Leionotus) fundatus Cresson, 1872) (Pierce 1911).

USA: Ilinois (Pierce 1911).

Euodynerus annulatus (Say, 1824) (as Leionotus verus (Cresson, 1872)) (Pierce 1909), Euodynerus foraminatus (Saussure, 1853) (Krombein 1967).

USA: Texas (Pierce 1909).

Montezumia centralis Zavattari, 1912 (as Montezumia huasteca var. centralis Zavattari, 1912) (Székessy 1965).

Honduras (Székessy 1965).

Eumenes sp. (Trois 1984b).

Brazil, Rio de Janeiro (Trois 1984b).

Probably misidentification of host. Eumenes does not occur in South America.

Parancistrocerus vagus (Saussure, 1857) (as Leionotus colon (Cresson, 1872)) (Pierce 1909).

USA: Louisiana, Texas (Pierce 1909).

Parancistrocerus vagus (Saussure, 1857) (as Leionotus vagans Saussure, 1857); Parancistrocerus histrio (Lepeletier, 1841) (as Odynerus (Ancistrocerus) histrio Lepeletier, 1841); Parancistrocerus pedestris (Saussure, 1855) (as Odynerus (Leionotus) pedestris Saussure, 1855) (Pierce 1909, 1911).

USA: Florida, Illinois, Louisiana, Nebraska (Pierce 1909, 1911).

Stenodynerus toas (Cresson, 1867) (as Odynerus taos Cresson, 1867) (Pierce 1919).

USA: New Mexico (Pierce 1919).

Hypodynerus vespiformis (Haliday, 1837), Hypodynerus coarctatus (Saussure, 1852), Monobia cingulata Brèthes, 1903 (Teson and Remes Lenicov 1979).

Chile; Argentina: Salta (Teson and Remes Lenicov 1979).

Stenodynerus histrionalis (Robertson, 1901) (as Odynerus (Ancistrocerus) histrionalis Robertson, 1901) (Pierce 1911).

USA: Illinois (Pierce 1911).

Ancistrocerus adiabatus (Saussure, 1853) (as Odynerus (Ancistrocerus) tigris Saussure, 1853) (Pierce 1911).

USA: Illinois (Pierce 1911).

Montezumia bruchii Brèthes, 1903 (as Montezumia vigilii Brèthes, 1910) (Brèthes 1923).

Argentina: Córdoba (Brèthes 1923); Venezuela (this study).

Differing from its sister genus Leionotoxenos by the shape of the periantennal area and the microstructure of the frontal area. Periantennal area expanded, sometimes raised, smooth (Fig. 29C). Distance between antennal area and supra-antennal sensillary field relatively large. Frontal region smooth or indistinctly wrinkled (Fig. 30B). Prosternum of most species of Eupathocera distinctly elevated above head medially and laterally, but apparently flat in Leionotoxenos (Fig. 29A). Rudiments of antennal torulus usually preserved (Fig. 29D). Sensilla restricted to clypeal lobe, not extended to ventral side of clypeal area. Mandible not protruding from capsule. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Shape and coloration. Compact, variable in shape, longer than wide to nearly as long as wide. Abdominal segment I sometimes protruding laterally, forming corner below spiracles (Fig. 28D). Very variable in size, length 1.02–2.47 mm, maximum width 0.88–2.5 mm. Anterior head margin evenly rounded or slightly protruding. Thorax slightly widening posteriorly. Coloration variable, with mostly dark or light brown pattern, but also patterns of multiple brown shades.

Figure 28. 

Eupathocera luctuosae (Pierce), host, female, cephalothorax, photomicrographs A Ammophila sp. stylopized by female of E. luctuosae, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax. Abbreviations: pp – pigmented papillae, sc – spiracular corner.

Figure 29. 

Eupathocera luctuosae (Pierce), female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviations: a – vestigial antenna, at – antennal torulus, lehc – lateral extension of head capsule, paa – periantennal area, pst – prosternum, ssf – supra-antennal sensillary field, sssf – sensillum of supra-antennal sensillary field.

Figure 30. 

Eupathocera luctuosae (Pierce), female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: fr – frontal region, ssf – supra-antennal sensillary field.

Head capsule. Ca. ¼ ~ ⅖ as long as entire cephalothorax including lateral cephalic extensions. Coloration rather pale to dark or forming specific patterns. Clypeal area well defined or not well delimited from labral area, with indistinct or slightly protruding clypeal lobe. Surface varying from wrinkled, lamellar, with scarcely visible sensilla, to completely smooth with distinctly exposed sensilla. Number of clypeal sensilla 20–80 or even more. Border between clypeal and frontal region clearly recognizable or indistinct but still present. Frontal region smooth or indistinctly wrinkled (Fig. 30B). Segmental border between head and prothorax distinct or only faintly recognizable on dorsal side.

Supra-antennal sensillary field. Smooth or slightly wrinkled, with dispersed sensilla (Fig. 29D). Not distinctly delimited by furrow medially, but border marked by different surface structure of supra-antennal sensillary field and smooth frontal region (Fig. 30B).

Antenna. Preserved as more or less clearly defined area. Antennal torulus usually reduced, preserved as interrupted furrow (Fig. 29D). Periantennal area expanded, sometimes raised, smooth (Fig. 29C). Distance between antennal area and supra-antennal sensillary field relatively large.

Labrum. Ventral field wider than long, elliptic to nearly circular. Dorsal labral field slightly arcuate, at least 4× wider than long in midline. Setae on dorsal field conspicuous, ~ 10–22.

Mandible. Anteromedially directed at an angle of 30–55°, enclosed in mandibular capsule. Mandibular bulge more or less distinctly raised, with ~ 5 indistinct sensilla. Cuticle of mandible smooth with longitudinal grooves or sculptured. Mandibular tooth narrow or slightly widened, with or without spines.

Maxilla. Reduced and not distinctly protruding, not projecting beyond mandible anteriorly. Partially fused to labial area, both regions often not clearly separated. Cuticle wrinkled or reticulated, in some cases with smooth areas. Vestige of palp inconspicuous, forming small bulge, sometimes very indistinct, located anteriorly or medially on ventral side of maxilla. Submaxillary groove indistinctly produced posteriorly to maxillary base.

Labium. Labial area more or less distinctly recognizable between maxillae, flat, longer than wide in midline or as long as wide. Anteriorly delimited by mouth opening, posteriorly by birth opening. Cuticular surface smooth or slightly reticulated.

Mouth opening. More or less arcuate, sclerotized along margin.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders variable, distinct or indistinct, usually indicated by mesal furrows, often combined with pigmented stripes. Border between metathorax and abdomen usually marked by change in cuticular surface structure or pigmentation. Cuticle of thoracic segments reticulate on ventral side, often with scattered small, pigmented papillae. Dorsal side of thorax smooth or slightly wrinkled. Prosternal extension undifferentiated, or anteriorly with specific color pattern. Prosternum distinctly elevated above head medially and laterally in most species (Fig. 29A). Shape of meso- and metathorax unmodified, transverse. Setae and cuticular spines present on lateral region of abdominal segment I (Fig. 29E).

Spiracles. Spiracles on posterior ~ ⅓ of cephalothorax slightly elevated, with anterolateral or anterodorsal orientation.

Differing from other genera in the following characters. Diameter of genae between maxillary base and compound eye at least 2× as large as diameter of vestigial antenna. Paired furrow of supra-antennal sensillary field indistinct or absent. Cephalotheca usually of nearly circular shape (Fig. 31A). Antennal diameter ca. as long as width of mandible (Fig. 31E). Mandible directed anteromedially.

Figure 31. 

Eupathocera cf. inclusa (Oliveira & Kogan), male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: a – vestigial antenna, fi – frontal impression, md – mandible, mx – vestige of maxilla.

Shape and coloration. In frontal view rounded, nearly circular, in lateral view pointed anteriorly. Coloration with a pattern of dark and slightly paler shades.

Cephalothecal capsule. Compound eyes with dark individual ommatidia well visible on paler ocular background. Very conspicuous clypeal lobe straight in frontal view, prominent in lateral view, bulging. Sensilla mainly concentrated on clypeal lobe. Frontal impression indistinct. Occipital bulge absent. Diameter of genae between maxillary base and compound eye large, > 2× as large as diameter of vestigial antenna.

Supra-antennal sensillary field. Kidney-shaped and bulging, delimited medially by weakly developed frontal impression. Distinct furrows not visible.

Vestigial antenna. Of standard shape, small, sometimes with incomplete torulus, and with small plates or cavities (Fig. 31C). Periantennal area not clearly delimited from supra-antennal sensillary field.

Labrum. Labral area distinct, with setae on dorsal field.

Mandible. Anteromedially directed. Tooth pointed, not reaching area of mandibular bulge basally. Bulge with sensilla.

Maxilla. Distinct, prominent, completely dark. Vestige of palp distinct.

Labium and hypopharynx. Labium distinct between and below maxillae, dark. Praementum and postmentum indistinctly separated by furrow. Hypopharyngeal protuberance absent.

Mouth opening. Poorly visible, partially covered by ventral labral field, arcuate.

According to Benda et al. (2019) part of a clade of a New World origin, also containing Leionotoxenos Pierce.

Including 16 valid species, restricted to the New World.

Various wasps from three families, but mostly sphecids (Sphecidae: Sphecinae, Ammophilinae), rarely Tachytes (Crabronidae: Crabroninae) and Zethus (Vespidae: Zethinae).

The genus Eupathocera was described by Pierce (1908) based on his concept that a new genus of Strepsiptera should be established if it utilizes a different host genus. The description of the male was too short and superficial. It was later synonymized with Pseudoxenos (Bohart 1937) and then with Paraxenos (Kinzelbach 1971b). We restore Eupathocera from synonymy and classify it as a valid genus, based on the molecular phylogeny (Benda et al. 2019, 2021) and morphological characters newly reported here. We classify the names Ophthalmochlus, Ophthalmochlus (Isodontiphila), Homilops, and Sceliphronechthrus as synonyms of Eupathocera. Based on morphological characters, species parasitising Pachodynerus (Vespidae) were assigned to Eupathocera.

Prionyx thomae (Fabricius, 1775) (as Proterosphex platensis Brèthes, 1908) (Brèthes 1923).

Argentina: Buenos Aires (Brèthes 1923).

Isodontia auripes (Fernald, 1906) (Pierce 1911); Isodontia mexicana (Saussure, 1867) (Benda et al. 2021).

USA: Maryland (Pierce 1911).

Ammophila sp. (Trois 1984a).

Brazil (Trois 1984a).

Prionyx atratus (Lepeletier, 1845) (as Priononyx atrata Lepeletier, 1845) (Pierce 1909).

USA: Ohio (Pierce 1909).

Pachodynerus erynnis (Lepeletier, 1941) (as Odynerus erynnys Lepeletier, 1941) (Pierce 1911).

USA: Florida (Pierce 1911), Colorado (this study).

This species has an lineage with unclear phylogenetic position (Benda et al. 2021). It is provisionally assigned to Eupathocera based on morphological characters. A more comprehensive sampling and a detailed study are necessary for a reliable classification of this taxon.

Sceliphron fasciatum (Lepeletier, 1845) (as Sceliphron (Pelopaeus) fasciatus Lepeletier, 1845) (Pierce 1909).

Dominican Republic: Santo Domingo (Pierce 1909).

Sphex servillei Lepeletier, 1845 (as Proterosphex fuliginosus Dahlbom, 1843) (Brèthes 1923); Sphex argentinus Taschenberg, 1869 (Benda et al. 2021).

Argentina: Tucumán (Brèthes 1923).

Ammophila sp. (Oliveira and Kogan 1963).

Brazil: Espírito Santo (Oliveira and Kogan 1963).

Pachodynerus cinerascens (Fabricius, 1775) (Kifune 1983).

Virgin Islands (Kifune 1983).

As Eupathocera erynnidis this species has an unclear phylogenetic position (Benda et al. 2021). It is also provisionally included in the genus Eupathocera Pierce, 1908, stat. res. based on morphological evidence.

Podalonia luctuosa (F. Smith, 1856) (as Sphex (Psammophila) luctuosa F. Smith, 1856) (Pierce 1911); Podalonia argentifrons (Cresson, 1865); Podalonia violaceipennis (Lepeletier, 1845) (Kinzelbach 1971b).

USA: Idaho, Colorado (Pierce 1911).

Ammophila aberti Haldeman, 1852 (as Sphex transversus Ferdanand, 1934); Ammophila arvensis Lepeletier, 1845 (as Sphex arvensis (Dahlbom, 1843)); Ammophila breviceps F. Smith, 1856 (= Sphex breviceps (F. Smith, 1856)); Ammophila extremitata Cresson, 1865; Ammophila fernaldi (Murray, 1938); Ammophila gracilis Lepeletier, 1845 (as Sphex (Ammophila) fragilis (F. Smith, 1856)); Ammophila kennedyi (Murray, 1938) (as Sphex (Ammophila) vulgaris (Cresson, 1865)); Ammophila nasalis Provancher, 1895 (as Sphex craspedotus Fernald, 1934 and S. nasalis (Provancher, 1895)); Ammophila pictipennis Walsh, 1869 (as Sphex (Ammophila) pictipennis (Walsh, 1869)); Ammophila pruinosa Cresson, 1865 (as Sphex (Ammophila) pruinosa (Cresson, 1865)); Ammophila urnaria Dahlbom, 1843 (as Sphex urnarius (Dahlbom, 1843)); Eremnophila aureonotata (Cameron, 1888) (as Sphex aureonotatus (Cameron, 1888)) (Pierce 1909; Bohart 1941; Kathirithamby et al. 2012; Cook 2019).

USA: Ohio, Colorado, Illinois, Iowa (Pierce 1909; Bohart 1941; Cook 2019).

Prionyx neoxenus (Kohl, 1890) (as Priononyx neoxenus, var. melanogaster Brèthes, 1910) (Brèthes 1923).

Argentina: Mendoza (Brèthes 1923).

Isodontia costipennis (Spinola, 1851) (Brèthes 1923).

Argentina: La Rioja (Brèthes 1923).

Prionyx fervens (Linnaeus, 1758) (as Priononyx striatus F. Smith, 1856) (Brèthes 1923).

Argentina: Córdoba (Brèthes 1923).

Prionyx pumilio (Taschenberg, 1869) (as Neosphex pumilio (Taschenberg, 1869) (Brèthes 1923).

Argentina: Mendoza (Brèthes 1923).

Sphex ichneumoneus (Linnaeus, 1758) (as Sphex aurocapillus Templeton, 1841; Sphex ichneumoneus aurifluus Perty, 1838; Proterosphex (Sphex) ichneumoneus Linnaeus, 1758); unknown name (Proterosphex (Sphex) pernanus Kohl) (Pierce 1909); Sphex pensylvanicus Linnaeus, 1763 (Miller et al. 2010); Tachytes sp. (this study).

Brazil: Rio de Janeiro (Templeton 1841); Dominican Republic: Santo Domingo; USA: Texas, Montana (Pierce 1909; Miller et al. 2010); Mexico (this study).

Maxilla reduced, not distinctly prominent (Fig. 34E). Two distinct dark spots present mesally on border between head and prothorax (Fig. 32D). Thoracic segments conspicuously sclerotized laterally from dorsal side (Fig. 32D). Lateral parts of abdomen posterior to spiracles always pale (Fig. 32D). Clypeal region bulging, very distinctly separated from labral area (Fig. 34D). Mandible not protruding from capsule. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Shape and coloration. Nearly as long as wide, or as long as or distinctly longer than wide. Very variable in size, length 0.8–1.82 mm, width 0.64–1.9 mm in midline. Anterior head margin evenly rounded or protruding. Thorax slightly or distinctly widening posteriorly. Cephalothorax with multiple brown shades forming distinct pattern.

Head capsule. Between ⅓ and > ½ × as long as entire cephalothorax including the lateral cephalic extensions. Coloration forming specific pattern with pale and dark shades. Clypeal region very distinctly delimited from labral area (Fig. 34D), arcuate, or protruding and forming clypeal lobe. Surface smooth or distinctly wrinkled. Sensilla mainly concentrated on clypeal lobe. Border between clypeal area and frontal region clearly indicated by change in cuticular surface. Cuticle of frontal area variable, distinctly wrinkled or covered with papillae. Border between head and prothorax usually distinct on dorsal side, delimited by transverse stripe of distinctive coloration and two distinct dark spots on mesal region (Fig. 32D).

Supra-antennal sensillary field. Smooth, with dispersed sensilla. Furrow between supra-antennal sensillary field and frontal region absent, or very indistinct and only indicated by change in cuticular sculpture (Fig. 34B).

Antenna. Preserved as poorly defined area, with several small, rounded plates, antennal sensilla, or cavity, in some cases all three combined. Periantennal area smooth or slightly wrinkled, sometimes indistinct.

Labrum. Ventral field wider than long, elliptic to nearly circular. Dorsal field arcuate, distinctly raised (Fig. 34D), sometimes very wide and narrow, ~ 5–8× wider than long in midline. Dorsal field with 14–41 (or more) setae or sensilla inserted in cavities.

Mandible. Anteromedially directed at angle of 30–35° and enclosed in mandibular capsule. Mandibular bulge distinctly raised, with several sensilla. Cuticle smooth or slightly sculptured, sometimes with longitudinal grooves (Fig. 34E). Tooth narrow or slightly widened, pointed apically or ventrally, more or less distinctly armed with spines.

Maxilla. Almost completely fused with labial area, or slightly raised (Fig. 34E), not projecting beyond mandible. Cuticle smooth or wrinkled. Vestige of palp present as cavity or poorly defined area; usually located medially on ventral side of maxilla (Fig. 34E). Submaxillary groove more or less distinctly produced anterolaterally to maxillary base.

Labium. Labial area between maxillae usually more or less distinct, delimited anteriorly by mouth opening and posteriorly by birth opening. Labial area wider than long in midline, flat or convex. Cuticular surface smooth or reticulated.

Mouth opening. Widely arcuate, sclerotized marginally.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders more or less distinct, usually separated by mesal furrows, rarely combined with pigmented stripes or spots on dorsal and ventral side. Border between metathorax and abdomen usually formed by ridge or indicated by change in cuticular sculpture. Cuticle of thoracic segments on ventral side reticulate, with scattered inconspicuous or more distinct pigmented papillae. Dorsal surface of thorax smooth or slightly reticulated. Prosternal extension undifferentiated or distinct, in some cases extremely elongated. Thoracic segments conspicuously sclerotized laterally from dorsal side (Fig. 32D). Shape of meso- and metathorax unmodified, transverse, or narrowed laterally in species with elongated head. Lateral parts of abdomen posterior to spiracles always pale (Fig. 32D). Setae present on lateral region of abdominal segment I (Fig. 33E, F).

Figure 32. 

Macroxenos cf. piercei, host, female, cephalothorax, photomicrographs A Anterhynchium flavomarginatum stylopized by female of M. cf. piercei, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax. Abbreviations: asI – abdominal segment I, sbhp – segmental border between head and prothorax, tx – thorax.

Figure 33. 

Macroxenos cf. piercei, female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F right lateral border of abdominal segment I below spiracle, dorsal side.

Figure 34. 

Macroxenos cf. piercei, female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: dlf – dorsal field of labral area, fr – frontal region, md – mandible, mx – vestige of maxilla, mxp – vestige of maxillary palp, sbcl – segmental border between clypeus and labrum, smxg – submaxillary groove, ssf – supra-antennal sensillary field.

Spiracles. Spiracles on posterior ~ ⅓ of cephalothorax slightly elevated, with anterodorsal and anterolateral orientation.

Male cephalotheca unknown.

The phylogenetic position is unstable. Benda et al. (2019) revealed it as sister to a lineage including Sphecixenos, Tuberoxenos, and Pseudoxenos in our concept. In contrast, Benda et al. (2021) resolved its position as sister to a clade including Sphecixenos, Tuberoxenos, Pseudoxenos, Deltoxenos, and Xenos. In both cases, the support was very weak. Further phylogenomic investigations with robust data are needed to resolve the intergeneric relationships.

A lineage of Australasian origin, with dispersion into the Indomalayan region (Benda et al. 2019). The two currently known species are restricted to these two biogeographic regions.

Various genera of Odynerini (Vespidae: Eumeninae).

The genus Macroxenos was described by Schultze (1925) but the descriptions of male and female was superficial. Later, Bohart (1937) synonymized it with Pseudoxenos. We classify this lineage as a separate genus, based on molecular phylogenies (Benda et al. 2019, 2021) and morphological characters newly reported here. However, this genus is quite complicated to diagnose because of a high morphological variability of species. More samples are still needed for a better characterization and recognition of this formerly overlooked group.

Allodynerus floricola (Saussure, 1852) (as Odynerus floricola Saussure) (Székessy 1956).

New Guinea (Székessy 1956).

The occurrence of Allodynerus in New Guinea is unlikely. Host identity thus requires a confirmation. Although only Macroxenos is known from the Australasian region as parasitic lineage of Odynerini wasps, we decided to assign this species to this genus preliminarily, pending a more detailed study in the future.

Rhynchium atrum Saussure, 1852 (Schultze 1925); Rhynchium atrissimum Vecht, 1968 (Kifune and Tano 1991).

Philippines: Luzon (Schultze 1925), Mindanao (Kifune and Tano 1991).

Kifune and Maeta (1965) proposed a new replacement name for Macroxenos piercei Schultze, 1925, a secondary homonym of Ophthalmochlus piercei Brèthes, 1923 (now Eupathocera piercei (Brèthes, 1923), comb. nov.) when both were placed in the same genus Pseudoxenos. Macroxenos piercei is reinstated here as a valid name following the Article 59.4 of ICZN (1999).

Paraxenos orientalis Kifune, 1985, here designated.

Differing from all other genera of Xenidae by very distinct prosternal features: prosternal extension anteriorly with very conspicuous, extensive pale spot, sometimes associated with cuticular impression (Figs 35C, 37A). A feature linked with the maxillae is shared with Paraxenos or Tuberoxenos: submaxillary groove distinctly produced posterolaterally to maxillary base (Fig. 37A), extending along cephalic border distally and then connected to border between head and prothorax. In contrast to Paragioxenos, head and prothorax ventrally delimited by birth opening medially and by suture laterally.

Figure 35. 

Sphecixenos orientalis, host, female, cephalothorax, photomicrographs A Sceliphron madraspatanum stylopized by female of S. orientalis, lateral view B detail of host abdomen with adult female inside C ventral side of cephalothorax D dorsal side of cephalothorax. Abbreviations: mxb – maxillary base, pps – prosternal pale spot.

Shape and coloration. Compact, ca. as long as wide, or slightly longer. Size variable, length 0.96–1.64 mm, maximum width 0.9–1.8 mm. Anterior head margin rounded, not protruding. Thorax slightly widening posteriorly. Abdominal segment I sometimes protruding laterally, forming rounded corner below spiracles. Coloration never completely pale, comprising multiple brown shades forming distinct patterns.

Head capsule. ~ ⅓ ~ ⅖ as long as entire cephalothorax including lateral cephalic extensions. Combination of pale and dark brown shades resulting in specific color pattern. Clypeal region well delimited from labral area, arcuate, without or with slightly protruding clypeal lobe. Surface smooth or slightly wrinkled. Sensilla (> 30) better visible in dorsal view than ventrally, concentrated mainly on anterior clypeal area. Border between clypeal region and frontal area indistinctly recognizable. Frontal area smooth or slightly reticulated. Dorsal border between head and prothorax indicated by interrupted suture or distinctive coloration, or scarcely recognizable.

Supra-antennal sensillary field. Smooth or slightly wrinkled, with evenly dispersed sensilla, not delimited or indistinctly delimited by furrow medially (Fig. 37B).

Antenna. Preserved as poorly defined area with several small, rounded plates, cavity, or sensilla. Periantennal area smooth (Fig. 36C).

Figure 36. 

Sphecixenos orientalis, female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F right lateral border of abdominal segment I below spiracle, dorsal side. Abbreviations: a – vestigial antenna, paa – periantennal area.

Labrum. Ventral field wider than long, elliptic. Dorsal field slightly arcuate, 3–4× wider than long in midline. Dorsal field with several inconspicuous setae, usually blunt, not pointed.

Mandible. Mandibles anteromedially directed at angle of 35–55°, enclosed in mandibular capsule. Mandibular bulge rounded or pointed, with several sensilla. Cuticle smooth, with longitudinal grooves. Tooth narrow, armed with spines.

Maxilla. Variable in shape, in some cases reduced and fused to labium, otherwise well-developed, separated from labial area, anteriorly directed, prominent but not projecting beyond mandible. Cuticle finely reticulated. Vestige of palp present as cavity with accessory plates or reduced. Submaxillary groove distinctly produced posterolaterally to maxillary base extending along cephalic border (Fig. 37A).

Figure 37. 

Sphecixenos orientalis, female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: fr – frontal region, fssf – furrow of supra-antennal sensillary field, pps – prosternal pale spot, sbhp – segmental border between head and prothorax, smxg – submaxillary groove, ssf – supra-antennal sensillary field.

Labium. Labial area between maxillae flat but distinct, delimited anteriorly by mouth opening and posteriorly by birth opening. Wider than long in midline or as long as wide. Cuticular surface smooth or reticulated.

Mouth opening. Distinctly arcuate to nearly straight, sclerotized marginally.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders relatively distinct, indicated by mesal furrows combined with stripes of specific coloration. Border between metathorax and abdomen usually indicated by change in cuticular surface structure or pigmentation. Cuticle of thoracic segments on ventral side reticulate with scattered small and pigmented papillae. Cuticle of dorsal side of thorax indistinctly reticulated. Prosternal extension differentiated anteriorly, with very conspicuous extensive pale spot, sometimes associated with cuticular impression (Figs 35C, 37A). Shape of meso- and metathorax unmodified, transverse. Setae on lateral region of abdominal segment I (Fig. 36E, F) present, or cuticular surface distinctly sculptured.

Spiracles. Spiracles on posterior third of cephalothorax slightly elevated, with lateral or anterolateral orientation.

Differing from other genera by large diameter of genae between maxillary base and compound eye, at least 2× as large as diameter of vestigial antenna. Distinct paired furrow of supra-antennal sensillary field absent. Cephalotheca nearly circular in frontal view (Fig. 38A). Diameter of vestigial antennae smaller than width of medially directed mandible (Fig. 38E).

Figure 38. 

Sphecixenos cf. gigas, male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: a – vestigial antenna, md – mandible, mx – vestige of maxilla.

Shape and coloration. In frontal view rounded, nearly circular, in lateral view rounded or slightly pointed anteriorly. With pattern of multiple shades of brown.

Cephalothecal capsule. Compound eyes with dark individual ommatidia well visible on paler ocular background. Clypeal lobe straight in frontal view, slightly protruding in lateral view. Sensilla mainly concentrated on medial clypeal region. Frontal impression indistinct. Occipital bulge absent. Diameter of genae between maxillary base and compound eye large, > 2× as large as diameter of vestigial antenna.

Supra-antennal sensillary field. Kidney-shaped and bulging, distinctly developed. Lacking distinct furrows medially.

Antenna. Of standard shape but very small, with small plates or cavities and complete torulus (Fig. 38C). Periantennal area not clearly delimited from supra-antennal sensillary field.

Labrum. Labral area distinct.

Mandible. Rather medially directed than anteromedially. Mandibular tooth pointed, not reaching area of mandibular bulge basally.

Maxilla. Distinct, prominent, with entirely dark coloration. Vestige of palp distinct.

Labium and hypopharynx. Dark labium distinct between and below maxillae. Praementum and postmentum separated by furrow. Hypopharyngeal protuberance not present.

Mouth opening. Clearly visible, not covered by ventral labral field, slightly arcuate.

According to Benda et al. (2019, 2021) sister to a monophyletic lineage containing Pseudoxenos and Tuberoxenos gen. nov.

This genus represents a lineage of Afrotropical origin which dispersed to Australia (Benda et al. 2019). It currently comprises 12 species, distributed in the Old World (mainly Afrotropical and Oriental regions) and Australian region.

Sphex, Isodontia (Sphecidae: Sphecinae), Sceliphron (Sphecidae: Sceliphrinae), and Chlorion (Sphecidae: Chloriontinae).

The name is derived from the family Sphecidae, the only known host family of this genus. The ending -xenos is used in several generic names, mainly in the family Xenidae. It is from a Greek substantive meaning enemy or stranger. Gender masculine.

All described species of Sphecixenos gen. nov. were previously placed in Paraxenos based on parasitising digger wasps (Kinzelbach 1971b). Despite this concept, this group is morphologically well defined. We classify it as a separate genus, based on the molecular phylogeny (Benda et al. 2019, 2021) and morphological characters newly reported here.

Sphex sp. (as Proterosphex sp.) (Pierce 1909).

Thailand: Trang (Pierce 1909).

Sphex cognatus F. Smith, 1856 (as Sphex formosus F. Smith, 1856) (Székessy 1956).

New Guinea: New Britain (Székessy 1956).

Chlorion sp. (Luna de Carvalho 1956); Sphex nigrohirtus Kohl, 1895 (Kinzelbach 1971b).

Angola (Luna de Carvalho 1956).

Sphex fumicatus Christ, 1791 (as Sphex metallicus Taschenberg, 1869) (Székessy 1956).

New Guinea (Székessy 1956).

Isodontia maidli (Yasumatsu, 1938) (Kifune and Tano 1985); Isodontia nigella (F. Smith, 1856) (as Sphex nigellus F. Smith, 1856) (Hirashima and Kifune 1962).

Japan (Hirashima and Kifune 1962).

Sphex lanatus Mocsáry, 1883; Sphex argentatus Fabricius, 1787 (as Sphex umbrosus Christ, 1791); Sphex fumicatus Christ, 1791 (as Sphex metallicus Taschenberg, 1869); Sphex schoutedeni Kohl, 1913 (as Isodontia (Proterosphex) schoutedeni Kohl, 1913); Isodontia stanleyi (Kohl, 1890) (as Sphex stanleyi Kohl, 1890) (Pasteels 1950; Kinzelbach 1971b).

Democratic Republic of Congo (Pasteels 1950).

Sphex madasummae Vecht, 1973 (Kifune 1984).

Philippines: Palawan (Kifune 1984).

Sceliphron laetum (Smith, 1856).

New Guinea; Australia: Queensland (Ogloblin 1926).

According to the article 34.2.1 of ICZN (1999), the ending of species name was adjusted to the grammatical gender of the new genus.

Sceliphron madraspatanum formosanum Vecht, 1968 (Kifune and Yamane 1985).

Japan: Iriomote and Ishigaki islands (Kifune and Yamane 1985); Laos; Thailand (this study).

Sphex tomentosus Fabricius, 1787 (as Sphex tuberculatum F. Smith, 1873) (Luna de Carvalho 1972).

Angola: Dundo (Luna de Carvalho 1972).

Isodontia praslinia (Guérin-Méneville, 1831) (as Sphex simplex Kohl, 1898) (Székessy 1956).

New Guinea (Székessy 1956).

Isodontia pelopoeiformis (Dahlbom, 1845) (as Chlorion (Isodontia) pelopaeiformis, Gerstaecker) (Pasteels 1952).

Democratic Republic of Congo (Pasteels 1952).

Pasteels (1952) probably misspelled the host name and the author of its description. Kinzelbach (1971b) probably overlooked these mistakes. We adjust it in accordance with Cook (2019).

Differs from Tuberoxenos by flat dorsal field of labrum (Fig. 41C) and more flattened cephalothorax, with more or less even shape (Fig. 39C), appearing flattened-elliptical in cross section. Distinguished from Deltoxenos by dorsal labral field laterally as long as along midline (Fig. 41C, D), and meso-metathoracic segmental border not constricted laterally. In contrast to Macroxenos lateral parts of abdomen posterior to spiracles with dark coloration (Fig. 39D). Mandible nested in mandibular capsule. In contrast to Paragioxenos, head and prothorax ventrally delimited by the birth opening in middle region and laterally by a suture.

Figure 39. 

Pseudoxenos sp., host, male, female, cephalothorax, photomicrographs A Paradontodynerus sp. stylopized by male of Pseudoxenos sp., lateral view B detail of host abdomen with male puparium inside C ventral side of female cephalothorax D dorsal side of female cephalothorax. Abbreviations: asI – abdominal segment I, sbhp – segmental border between head and prothorax.

Shape and coloration. Compact, longer than wide, elliptic in cross-section. Meso-metathoracic segmental border not constricted laterally. Size fairly constant, length 1.08–1.44 mm, maximum width 1.02–1.4 mm. Anterior head margin rounded or protruding. Thorax slightly widening posteriorly. Coloration with multiple brown shades forming pattern.

Head capsule. Ca. ⅖ as long as entire cephalothorax including lateral extensions. Coloration mostly dark brown, often with specific patterns. Clypeal region delimited from labral area (Fig. 41D), arcuate, or protruding and forming clypeal lobe. Surface smooth or slightly wrinkled. Approximately 35–56 sensilla mainly concentrated anteriorly but dispersed over entire clypeal area. Border between clypeal area and frontal region hardly distinct but still recognizable. Frontal surface smooth (Fig. 40F). Segmental border between head and prothorax clearly recognizable or indistinct on dorsal side, often indicated by dark brown stripes, and in some cases with two distinct dark spots on mesal region (Fig. 39D).

Figure 40. 

Pseudoxenos sp., female, cephalothorax, SEM micrographs A ventral side B dorsal side C left vestigial antenna, dorsal side D right vestigial antenna, dorsal side E left lateral border of abdominal segment I below spiracle, dorsal side F detail of anterior border of cephalothorax, dorsal side. Abbreviations: a – vestigial antenna, fr – frontal region.

Figure 41. 

Pseudoxenos sp., female, cephalothorax, SEM micrographs A anterior part of cephalothorax, ventral side B anterior part of cephalothorax, dorsal side C mouthparts, ventral side D detail of anterior border of cephalothorax, ventral side E right mandible and maxilla, ventral side F left mandible and maxilla, ventral side. Abbreviations: dlf – dorsal field of labral area, fr – frontal region, fssf – furrow of supra-antennal sensillary field, mx – vestige of maxilla, sbhp – segmental border between head and prothorax, ssf – supra-antennal sensillary field.

Supra-antennal sensillary field. Smooth or slightly wrinkled, with dispersed sensilla. Furrow forming border on medial side more or less distinct (Fig. 41B).

Antenna. Preserved as poorly defined area, sometimes raised, usually with several small, rounded plates, rarely with additional sensilla or cavity (Fig. 40C). Periantennal area smooth.

Labrum. Ventral field distinctly wider than long, elliptic. Dorsal field nearly straight, slightly arcuate, at least 4–5× wider than long in midline, flat and smooth, with 15–21 clearly visible setae inserted in cavities (Fig. 41C, D). Dorsal field laterally as long as medially, in some cases almost merging with head capsule.

Mandible. Mandibles anteromedially directed at an angle of 35–45° and nested in mandibular capsule. Mandibular bulge not or slightly raised, bears several sensilla. Cuticle of mandible sculptured to nearly smooth. Mandibular tooth narrow, pointed, straight or hook-shaped, armed with spines.

Maxilla. Separated from labial area, slightly or distinctly protruding, prominent portion directed anteriorly or anterolaterally, maxilla slightly overlapping with mandible proximally (Fig. 41F), but not projecting beyond it anteriorly. Cuticle usually smooth, rarely wrinkled. Vestige of palp very distinct, with more or less distinct plates or cavity, located medially on ventral side of maxilla. Submaxillary groove more or less distinctly produced posterolaterally to maxillary base.

Labium. Labial area between maxillae flat but distinct, relatively large, delimited anteriorly by mouth opening and posteriorly by birth opening. As long as wide or longer than wide. Cuticular surface in most cases largely smooth and shiny, or faintly and uniformly sculptured.

Mouth opening. Mouth opening arcuate, nearly straight, or bi-arcuate, sclerotized marginally.

Thorax and abdominal segment I. Pro-mesothoracic and meso-metathoracic borders more or less distinct, separated by mesal furrows. Border between metathorax and abdomen formed by ridge. Cuticle of thoracic segments on ventral side reticulate with scattered small and pigmented papillae. Cuticle of dorsal side of thorax smooth or slightly wrinkled. Prosternal extension undifferentiated, anterior margin evenly arched. Meso- and metathorax transverse. Lateral parts of abdomen posterior to spiracle dark (Fig. 39D). Setae present on lateral region of abdominal segment I.

Spiracles. Spiracles on posterior ⅓ of cephalothorax slightly elevated, with anterolateral or lateral orientation.

Diameter of genae between maxillary base and compound eye ~ 1.5× as large as diameter of vestigial antenna. Occipital bulge present (Fig. 42D). Frontal region very distinctly deformed by frontal impression (Fig. 42D). Distinct paired furrows of supra-antennal sensillary field absent.

Figure 42. 

Pseudoxenos sp., male, cephalotheca, photomicrographs, SEM micrographs A frontal view B lateral view C vestigial antenna D frontal view E mouthparts. Abbreviations: fi – frontal impression, ob – occipital bulge.